It is desired in many instances to control the temperature at which exhaust gasses are exhausted into the atmosphere, and to maintain the temperature of exhaust gasses below certain thresholds at given distances from the vehicle, to alleviate the impact that exhaust heat can have on the vehicle's immediate environment.
Further, the importance of exhaust gas treatment units in exhaust systems of diesel engine vehicles has considerably increased during past years, much with the trend to obtain “cleaner” emissions or “greener” vehicles. Diesel particle filters, or DPFs, which can reduce particulate emissions, and selective catalytic reduction units, or SCRs, which can reduce NOx emissions, are two examples of exhaust gas treatment units which can be used with diesel engine vehicles.
There is a drawback of some exhaust gas treatment units which is related to the fact that they can emit a relatively large amount of heat into the exhaust gasses. The consideration of their use imposes an additional burden with respect to heat management. Diesel particle filters (DPFs), for instance, accumulate particulate matter or soot. To get rid of the accumulated matter in the particle filter, a process referred to as filter regeneration can be used. Heat regeneration is a commonly used filter regeneration technique which involves increasing the temperature of the accumulated particles until they ignite or combust. The increase of temperature can be caused for example by a fuel burner, or through engine management techniques which cause the exhaust gasses to reach predetermined burning temperatures. The resulting increase in temperature can be felt in the exhaust gasses themselves, and dealing with the heat generated in the exhaust gasses during heat regeneration can thus pose an important design challenge in certain types of vehicles.
There thus remained several needs which remained to be addressed in relation with engine and/or exhaust system heat evacuation and temperature control of exhausting gasses.